This invention relates generally to an apparatus for maintaining an orientation of a bearing member with an actuator and, more particularly, to an apparatus for maintaining an orientation of a bearing member pivotally attached to an actuator rod with respect to an axis of the rod.
It is often desired in machine applications to drive a component which pivots in a rotating fashion by an actuator component which moves in a linear direction. For example, internal combustion engines often include rocker arms which pivot about a point to control operation of valves, injectors, and the like. The rocker arms are themselves driven by rods which push against one end of the rocker arm in a linear motion.
The juncture of a linear motion part with an angular motion part results in unequal and erratic contact of the surfaces of the two parts. A rod with an essentially flat end, contacting a portion of a rocker arm with an essentially flat end, results in an inability to maintain full contact of the flat surfaces as the rocker arm pivots. This inability results in stresses on the components and wear of the material.
Historically, manufacturers of these components have attempted to compensate by such means as rounding the tips of the rods to try to maintain a more consistent contact area between the rods and the rocker arms. Design changes such as these have met with limited success.
More recent design attempts have incorporated bearing members, such as buttons or feet, between the rods and the rocker arms. These bearing members typically pivotally attach to the rods and have flat outer surfaces designed to engage the rocker arms more evenly and consistently. Examples of this approach may be found in U.S. Pat. No. 5,165,375 to Hu, U.S. Pat. No. 5,195,489 to Reich, and U.S. Pat. No. 5,365,916 to Freiburg et al., in which a bearing member of some kind is pivotally attached to a substantially spherically shaped end of a push rod, the bearing member having a flat surface to maximize engagement with a rocker arm.
In each of the above cases, attempts are made to maintain a desired alignment between the rods and the bearing members by the use of springs, clips, o-rings, and the like located where the rods and the members contact each other. These attempts, however, do not ensure that alignment will be maintained, and also may contribute to wearing and eventual breakdown of the contact surfaces.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention an apparatus for aligning a bearing member with an actuator is disclosed. The apparatus includes an actuator having a substantially cylindrical shape and disposed about an axis, a substantially spherical end on the actuator, a bearing member having a substantially spherical opening for housing the spherical end, the spherical end and the spherical opening being configured such that the bearing member is held in swiveling contact by the spherical end, a spring retainer located on the actuator a desired distance from the spherical end, and a spring located about the actuator from the spring retainer to the bearing member such that a spring force is placed on the bearing member to maintain alignment of the bearing member with the axis.